Combination Liquid-Cooled Exhaust Manifold Assembly And Catalytic Converter Assembly For A Marine Engine

ABSTRACT

An exhaust system for a marine engine comprising liquid cooled manifold and catalytic converter assemblies. Each assembly uses a separate cooling system to cool either the exhaust manifold or a shell inside which resides the catalytic converter. The housing or shell containing the catalytic converter uses water to cool an exterior surface of a water jacket to an acceptable temperature conforming to federal regulations. The liquid-cooled manifold assembly may use either water or glycol to cool a jacket surrounding tubes extending from the engine block to the catalytic converter assembly.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of the filing of U.S. provisional Patent Application. Ser. No. 61/209,772, filed Mar. 11, 2009 entitled “Combination Liquid-Cooled Exhaust and Catalytic Converter For a Marine Engine” which is fully incorporated herein.

FIELD OF THE INVENTION

The present invention relates to exhaust systems for combustion engines and, more particularly, to the exhaust manifold and catalytic converter of such exhaust systems.

BACKGROUND OF THE INVENTION

Exhaust systems for a combustion engine generally include a manifold connected to the combustion engine at one end and bolted to an exhaust pipe at the other end. The exhaust pipe extends a distance from the manifold and generally has a catalytic converter system bolted thereto. These catalytic converter systems generally include a ceramic substrate having a catalyst coated thereon and a metal housing surrounding the substrate. In general, the catalysts require a minimum temperature to react with the emissions and reduce them. Higher reaction temperatures enhance the removal of harmful emissions from the exhaust gases. The core temperature of conventional catalytic converters is typically 1,000 to 1,400 degrees Fahrenheit. In automobile applications, the exterior surfaces of the catalytic converters are air cooled, rather than water cooled, to a temperature of about 600 to 1,000 degrees Fahrenheit. Such high temperature far exceeds the 200 degrees Fahrenheit set by the United States Coast Guard for the exterior temperature of the exhaust system of inboard or stern drive engines.

Although catalytic converters have been required in cars for many years, they have not been required in marine vessels with inboard or stern drive engines. However, in 2009, catalytic converters began being required by federal law in new marine vessels with inboard or stern drive engines. This requirement is challenging because it has been difficult to maintain a sufficiently cooled exterior temperature for marine applications while also maintaining a sufficiently high enough temperature in the element or core of the catalytic converter. The United States Coast Guard has a limit of 200 degrees Fahrenheit for the exterior temperature of the exhaust system of inboard or stern drive engines. The United States Environmental Protection Agency (“USEPA”) has emissions standards which require use of a catalytic converter in inboard or stern drive engines.

One known method of reducing the exterior temperature of the housing in which resides a catalytic converter for a marine vessel is to water cool the housing. This concept is disclosed in U.S. Patent Publication No. US 2009/0175772, published Jul. 9, 2009.

However, there is a need to maintain all exposed surfaces below the 200 degrees Fahrenheit limit by surrounding the exhaust manifold with liquid to cool the tubes containing the exhaust prior to these exhaust gases entering a liquid cooled catalytic converter.

SUMMARY OF THE INVENTION

According to embodiments of the present invention, an exhaust system for a marine engine comprises the combination of a liquid-cooled exhaust manifold assembly and a liquid-cooled catalytic converter assembly. The exhaust manifold comprises individual tubular exhaust runners extending from each cylinder of a marine engine to the catalytic converter assembly. These tubular exhaust runners are the same length, but twisted, optimized in size and shape, to give optimal engine performance. The catalytic converter assembly, located downstream of the liquid-cooled exhaust manifold assembly, functions to control engine exhaust emissions exiting the liquid-cooled exhaust manifold assembly.

The exhaust manifold assembly further comprises a manifold jacket surrounding the tubular exhaust runners. In one embodiment, the manifold jacket is made of two pieces of sheet metal, the manifold jackets being shaped like a clam shell. Liquid in the form of water or glycol is circulated from a first pump through this manifold jacket so as to always maintain the outside temperature of the manifold jacket at less than 200° F. whenever the engine to which the manifold is connected is operated.

In one embodiment, the manifold jacket surrounding the tubular runners of the manifold assembly is made from two shaped sheet metal panels which are welded together and welded to stubs welded to a mounting plate and a sheet metal baffle. Ports or bosses on the manifold assembly are provided for the in-flow and out-flow of water or glycol through the manifold assembly. Similarly, an inlet port is provided for supplying cooling water to fluid passage surrounding a catalytic converter housing to cool and maintain the outside surface of the catalytic converter assembly below a predetermined temperature. This water passage surrounding the catalytic converter discharges the water into the exhaust gases at the discharge end of the catalytic converter assembly.

Water from a second pump is also circulated through a fluid passage surrounding the catalytic converter housing so that the catalytic converter is always water-cooled and the outside temperature of the converter assembly maintained at a temperature of less than 200° Fahrenheit when the engine is operated. From the exhaust or downstream side of the catalytic converter assembly, the water from the fluid passage flows around the catalytic converter assembly inner shell and is mixed with exhaust gases to be discharged with the exhaust gases after the gases have passed through the catalytic converter.

According to another aspect of the present invention, the exhaust system for a marine engine comprises: a liquid-cooled catalytic converter assembly including a catalytic converter fixed inside an inner shell and an outer shell surrounding the inner shell, the inner and outer shells defining a fluid passage therebetween. The outer shell is joined to the inner shell proximate an inlet end of the catalytic converter assembly. The outer shell has a fluid inlet in fluid communication with the fluid passage to introduce fluid into the fluid passage to cool and maintain the outside surface of the catalytic converter assembly below a predetermined temperature when liquid passes through the fluid passage.

The liquid-cooled exhaust manifold assembly comprises a plurality of tube stubs welded to a mounting plate, a baffle and a plurality of tubular exhaust runners secured to the baffle and the mounting plate and extending therebetween. The exhaust manifold assembly further comprises a manifold jacket surrounding the tubular exhaust runners, the manifold jacket having an inlet for introducing fluid inside the manifold jacket and an outlet for removing fluid from the manifold jacket to cool the outside surface of the manifold jacket to maintain the outside temperature of the manifold jacket below a predetermined temperature.

According to another aspect of the present invention, the exhaust system for a marine engine comprises a liquid-cooled exhaust manifold assembly and a liquid-cooled catalytic converter assembly downstream of the manifold assembly. The catalytic converter assembly includes a catalytic converter, an inner shell and an outer shell surrounding the inner shell. The inner and outer shells define a fluid passageway therebetween. The outer shell has a fluid inlet in fluid communication with the fluid passage to introduce fluid into the fluid passage to cool and maintain the outside surface of the catalytic converter assembly below a predetermined temperature when liquid passes through the fluid passage.

The liquid-cooled exhaust manifold assembly comprises a mounting plate for securing the exhaust system to the marine engine, a plurality of tube stubs welded to the mounting plate, a baffle and a plurality of exhaust runners. Each of the exhaust runners is welded to the mounting plate at one end and to the baffle at the other end. The baffle is welded to the catalytic converter assembly. The manifold assembly further comprises a manifold jacket comprising upper and lower half shells welded together and surrounding the exhaust runners. The manifold jacket has an inlet for introducing fluid inside a fluid cavity defined by the manifold jacket, baffle and tube stubs, and an outlet for removing fluid from the manifold jacket to cool the outside surface of the manifold jacket to maintain the outside temperature of the manifold jacket below a predetermined temperature.

Thus the exhaust system of the present invention has two separate cooling systems, each one functioning to cool the exterior temperature of a part of the exhaust system. These and other objects and advantages will be more readily apparent from the following drawings and detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an exhaust system in accordance with the present invention;

FIG. 2 is a perspective view of the exhaust system of FIG. 1, a portion being cutaway;

FIG. 3 is a disassembled view of the liquid-cooled exhaust manifold assembly of FIG. 1;

FIG. 3A is a partially disassembled view of a portion of the exhaust system of FIG. 1;

FIG. 4 is a cross sectional view of a portion of the exhaust system of FIG. 1;

FIG. 5 is a view taken along the line 5-5 of FIG. 4;

FIG. 6 is schematic illustration of the flow of fluids in accordance with one embodiment of the invention;

FIG. 6A is a schematic illustration of the flow of fluids in accordance with another embodiment;

FIG. 7 is a view taken along the line 7-7 of FIG. 1; and

FIG. 8 is a bottom perspective view of the exhaust system of FIG. 1.

It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various features illustrative of the basic principles of embodiments of the invention. The specific design features of embodiments of the invention as disclosed herein, including, for example, specific dimensions, orientations, locations and shapes of various illustrated components, as well as specific sequences of operations (e.g., including concurrent and/or sequential operations), will be determined in part by the particular intended application and use environment. Certain features of the illustrated embodiments may have been enlarged or distorted relative to others to facilitate visualization and clear understanding.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring to the drawings, and particularly to FIG. 1, there is illustrated a diagrammatic illustration of an exhaust system 10 for a marine engine 12 (shown in phantom in FIG. 1). Arrows 14 are shown in FIG. 1 illustrating exhaust gases exiting the cylinders of the marine engine 12 and entering the exhaust system 10. Although the drawings illustrate the engine 12 having four cylinders, those skilled in the art will appreciate that the present invention may be used with two cylinder marine engines or any other like engine.

The exhaust system 10 comprises a combination of two basic components: a liquid-cooled exhaust manifold assembly 16 and a liquid-cooled catalytic converter assembly 18 located downstream of the exhaust manifold assembly 16. In order to assemble the exhaust system 10, the two components, the liquid-cooled exhaust manifold assembly 16 and a liquid-cooled catalytic converter assembly 18, are welded together.

Referring to FIGS. 3 and 3A, the components of the liquid-cooled exhaust manifold assembly 16 will be described. The liquid-cooled exhaust manifold assembly 16 comprises a mounting plate 20 made of steel having mounting holes 22 therethrough for mounting the liquid-cooled exhaust manifold assembly 16 to the engine block 12 with fasteners (not shown). See FIG. 3A. The mounting plate 20 also has a plurality of spaced exhaust holes 24 therethrough which allow the exhaust gases to pass through the mounting plate 20 and into the catalytic converter assembly 18 via tubular exhaust runners 26.

As shown in FIGS. 3A and 7, a plurality of tube stubs 28 (one per each exhaust hole 24 of mounting plate 20) are secured via welds 124 to mounting plate 20, secured to the lower half shell 36 of the manifold jacket 32 with welds 122 and extend upwardly from the mounting plate 20. Each tube stub 28 has a hollow interior into which one of the tubular exhaust runners 26 fits. The tube stubs 28 provide welding surfaces to which the lower half shell 36 of the manifold jacket 32 of the exhaust manifold assembly 16 is welded, as described below.

As shown in FIGS. 3A and 7, each of the tubular exhaust runners 26 is welded at one end to one of the tube stubs 28 at weld 124. The other end of each of the hollow tubular exhaust runners 26 is welded to a baffle 30. Each of the tubular exhaust runners 26 is the same length to optimize engine performance. During operation of the marine engine 12, exhaust gases pass through the interior of the tubular exhaust runners 26 into the catalytic converter assembly 18. See FIG. 4.

As best shown in FIG. 3, exhaust manifold assembly 16 further comprises a manifold jacket 32 comprising an upper half shell 34 and a lower half shell 36, shown separated in FIGS. 3 and 3A. The manifold jacket 32 is made of sheet metal and is shaped like a clam shell. Each of the pieces 34, 36 of the manifold jacket 32 is shaped like half a clam shell.

As shown in the drawings, a first boss 38 having a passage 40 therethrough is welded to the outer surface of lower half shell 36 around an opening 42 (see FIGS. 3 and 3A) through the lower half shell 36 to create a fluid inlet 44. Similarly, a second boss 46 having a passage 48 therethrough is welded to the outer surface of lower half shell 36 around an opening 50 (see FIGS. 3 and 3A) through the lower half shell 36 to create a fluid outlet 52.

As shown in FIG. 3, upper half shell 34 has an opening 120 around which is welded a boss 126 having a passage 128. As shown in FIG. 2, boss 126 is adapted to receive a bleed valve 75 to remove excess air when the fluid cavity 54 described below is filled with fluid.

As shown in FIGS. 7 and 8, the upper and lower half shells 34, 36 are welded together with a continuous weld 56, the upper half shell 34 fitting over a portion of the lower half shell 36 in a “shoebox” manner. As shown in FIG. 7, the lower half shell 36 is welded to the tube stubs 28 at welds 122 and the upper half shell 34 is welded to the lower half shell 36 at weld 56.

As shown in FIG. 2, fluid cavity 54 is defined by the upper and lower half shells 34, 36 welded together, the baffle 30 welded to one end of the tubular exhaust runners 26 and the mounting plate 20 secured to the other ends of the tubular exhaust runners 26. As shown in FIG. 2, exhaust from the marine engine 12 passes through the tubular exhaust runners 26 into the catalytic converter assembly 18. This exhaust is cooled by either glycol or water passing through the fluid cavity 54, the fluid entering fluid cavity 54 via fluid inlet 44 and exiting fluid cavity 54 via fluid outlet 52, as shown in FIGS. 6 and 6A.

According to one aspect of the invention shown in FIG. 6, glycol from a fluid source 66 is pumped via a first pump 60 via conduit or pipe 62 to the fluid inlet 44, through the fluid cavity 54 of the exhaust manifold assembly 16, out the fluid cavity 54 via fluid outlet 52 and passes via conduit or pipe 64 back to the fluid source 66. This is considered a closed loop system and used primarily for use in salt water to prevent corrosion of the tubular exhaust runners 26.

According to another aspect of the invention shown in FIG. 6A, water from a fluid source 68 is pumped via a first pump 70 via conduit or pipe 72 to the fluid inlet 44, through the fluid cavity 54 of the exhaust manifold assembly 16, out the fluid cavity 54 via fluid outlet 52 and passes via conduit or pipe 74 back to the fluid source, which is commonly the water of a water body on which the boat is used. This is considered an open system and used primarily for use in fresh water without affecting the tubular exhaust runners 26 which are exposed to the fluid of the fluid cavity 54 in both embodiments.

FIGS. 4 and 5 illustrate the liquid-cooled catalytic converter assembly 18 which comprises a catalytic converter 76 held in place via a compressible mat 78 inside an inner shell or housing 80. An outer shell 82 surrounds the inner shell 80 and is welded to the inner shell 80 at location 84 proximate an inlet 86 to the liquid-cooled catalytic converter assembly 18 and at locations 88 proximate bosses 90. Bosses 90 are adapted to receive oxygen sensors 92 which help determine whether catalytic converter 76 is functioning properly. A fluid passage 94 is defined between the inner and outer shells 80, 82. As shown in FIGS. 4 and 5, the inner shell 80 is not concentric with the outer shell 82 proximate an outlet 96 of the liquid-cooled catalytic converter assembly 18. Therefore, as shown in FIG. 5, the fluid passage 94 is crescent-shaped in cross-section proximate the outlet 96 of the catalytic converter assembly 18.

A boss 98 having a passage 100 therethrough is welded to the outer shell 82 around an opening 102 (see FIG. 4) through the outer shell 82 to create a fluid inlet 104. Water or some other fluid is pumped from fluid pump 106 through the fluid inlet 104 into the fluid passage 94. The fluid is illustrated by the arrows 108 in FIG. 4, while the exhaust is illustrated by arrows 110. After the fluid exits the fluid passage 94, it is mixed with the exhaust gases and both together exit the outlet of the liquid-cooled catalytic converter assembly 18. As illustrated in FIGS. 6 and 6A, fluid such as water from a fluid source 112 is pumped via a pump 114 via conduit or line 116 into the fluid inlet 104 of the liquid-cooled catalytic converter assembly 18. The fluid is then passed through the fluid passage 94 and exits the liquid-cooled catalytic converter assembly 18, as indicated by the arrows 118.

While the present invention has been illustrated by a description of the various embodiments, and while these embodiments have been described in considerable detail, it is not the intention to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. Thus, the invention in its broader aspects is therefore not limited to the specific details, representative apparatus and method, and illustrative examples shown and described. In particular, a person having ordinary skill in the art will appreciate that any of the blocks of the above flowcharts may be deleted, augmented, made to be simultaneous with another, combined, or be otherwise altered in accordance with the principles of the embodiments of the invention. Accordingly, departures may be made from such details without departing from the spirit or scope of applicant's general inventive concept.

Although we have described various embodiments of the invention, we do not intend to be limited except by the scope of the following claims. 

1. An exhaust system for a marine engine, comprising: a combination of a liquid-cooled exhaust manifold assembly and a liquid-cooled catalytic converter assembly, which liquid-cooled exhaust manifold assembly comprises a manifold jacket surrounding tubular exhaust runners extending from cylinders of the marine engine to the catalytic converter assembly, liquid being supplied to and from the manifold jacket to cool the outside surface of the manifold jacket to maintain the outside temperature of the manifold jacket below a predetermined temperature, and liquid being supplied to and from a fluid passage surrounding a catalytic converter housing to cool and maintain the outside surface of the catalytic converter assembly below a predetermined temperature.
 2. The system of claim 1 wherein said manifold jacket is made of sheet metal.
 3. The system of claim 1 wherein said manifold jacket is shaped like a clam shell.
 4. The system of claim 1 wherein said manifold jacket is made from multiple pieces welded together.
 5. The system of claim 1 wherein each of the tubular exhaust runners is approximately the same length.
 6. The system of claim 1 wherein the liquid being supplied to and from the housing to cool the outside surface of the manifold is water.
 7. The system of claim 1 wherein the liquid being supplied to and from the housing to cool the outside surface of the manifold is glycol.
 8. An exhaust system for a marine engine, comprising: a liquid-cooled catalytic converter assembly including a catalytic converter fixed inside an inner shell and an outer shell surrounding the inner shell, the inner and outer shells defining a fluid passage therebetween, the outer shell being joined to the inner shell proximate an inlet end of the catalytic converter assembly, wherein the outer shell has a fluid inlet in fluid communication with the fluid passage to introduce fluid into the fluid passage to cool and maintain the outside surface of the catalytic converter assembly below a predetermined temperature when liquid passes through the fluid passage; and a liquid-cooled exhaust manifold assembly comprising a plurality of tube stubs welded to a mounting plate, a baffle, and a plurality of tubular exhaust runners welded to the baffle and the mounting plate and extending therebetween, said exhaust manifold assembly further comprising a manifold jacket surrounding the tubular exhaust runners and being welded to the baffle and the tube stubs, said manifold jacket having an inlet for introducing fluid inside said manifold jacket and an outlet for removing fluid from the manifold jacket to cool the outside surface of the manifold jacket to maintain the outside temperature of the manifold jacket below a predetermined temperature.
 9. The system of claim 8 wherein said manifold jacket is made from sheet metal.
 10. The system of claim 9 wherein said manifold jacket is shaped like a clam shell.
 11. The system of claim 8 wherein said manifold jacket is made from multiple parts.
 12. The system of claim 8 wherein said catalytic converter assembly has bosses adapted to receive oxygen sensors.
 13. The system of claim 8 wherein said exhaust manifold assembly has four tubular exhaust runners.
 14. The system of claim 8 wherein said tubular exhaust runners of said exhaust manifold assembly are welded to stubs welded to said mounting plate of said exhaust manifold assembly.
 15. An exhaust system for a marine engine, comprising: a liquid-cooled catalytic converter assembly including a catalytic converter, an inner shell and an outer shell surrounding the inner shell, the inner and outer shells defining a fluid passageway therebetween, wherein the outer shell has a fluid inlet in fluid communication with the fluid passage to introduce fluid into the fluid passage to cool and maintain the outside surface of the catalytic converter assembly below a predetermined temperature when liquid passes through the fluid passage; and a liquid-cooled exhaust manifold assembly comprising a mounting plate for securing the exhaust system to the marine engine, a plurality of tube stubs welded to the mounting plate, a baffle, and a plurality of exhaust runners, each of said exhaust runners being welded to the mounting plate at one end and to the baffle at the other end, said baffle being welded to the catalytic converter assembly, said manifold assembly further comprising a manifold jacket comprising upper and lower half shells welded together and surrounding the exhaust runners, said manifold jacket having an inlet for introducing fluid inside a fluid cavity defined by said manifold jacket, said baffle and said tube stubs and an outlet for removing fluid from the manifold jacket to cool the outside surface of the manifold jacket to maintain the outside temperature of the manifold jacket below a predetermined temperature.
 16. The system of claim 15 wherein said manifold jacket is made from multiple pieces of sheet metal.
 17. The system of claim 15 wherein said catalytic converter assembly has bosses adapted to receive oxygen sensors.
 18. The system of claim 15 wherein said exhaust manifold assembly has four tubular exhaust runners.
 19. The system of claim 15 wherein said exhaust runners of said exhaust manifold assembly are tubular.
 20. The system of claim 15 wherein each of the exhaust runners is approximately the same length. 